Control of electroresponsive devices



July 29, 1930," I iwmmm r AL 1,771,935

CONTROL OF ELECTRORESPONSIVE DEVICES Original Filed Dec. 31, 1923 Inve nliors: John E Tr'ltle, Jacob \M No Nairy, y Mil/L2:

Thai? Attorney.

Patented July 29, 1930 UNITED STATES" PATENT OFFICE I JACOB W. MGNAIRY AND JOHN F. TNITLE, 0F SCHENECTADY, NEW YORK, ASSIGNOBS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK CONTROL OF ELECTRORESPONSIVE DEVICES Original application filed December 81, 1923, Serial No. 683,533. Divided and this application filed February '2, 1925. Serial No. 6,204.

Our present invention relates to improve ments in the control of electroresponsive devices and more particularly to the control of electromagnetic circuit interruptors and the like which are movable to one-positionand biased to another position and are arranged to be operated to the one position by one electromagnet and held in the one position by another electromagnet, and the invention has for its principal object the provision of improved systems and apparatus for controlling the operation of such devices.

This application is a division of our former application, Serial No. 683,533, filed December 31, 1923.

WVhen an electromagnetic device of the above character is operated to the one posi tion against its bias to the other position, the device may not be held by the holding electromagnet due to the jar or shock accompanying the operation of the device to the said one position by the operating electromagnet. Therefore, one of the specific objects of our invention is to prevent the occurrence of this undesirable result.

This objectis accomplishedin accordance with the present invention by providing a device of the above character with means for controlling the operating electromagnet and at the same time regulating the active force or" the holding electromagnet while the device is being operated to the one position so as to thereby ensure that the device will be positively held by the electromagnet. In carrying the invention into eiiect in a preferred form, we provide means for automatically increasing the excitation of the holding electromagnet while the device is being operated by the operating.electromagnet into attractive relation therewith and until after the operating electromagnet is rendered inactive thereby leaving the device entirely under the control of the holding electromagnet.

Although our invention has a wide field of application, it is. however, of particular utility when embodied in high speed, trip free, circuit intcrruptors of the type described and claimed in Patent No. 1,560.440. issued November 3, 1925, upon the application of Johii F. Tritle, and assigned to the same assignee as our present invention. In the Tritle type of interruptor, the movable magnetic member of anelectromagnet is strongly biased to the unattracted position and carries a relatively movable switch arm which is biased to the closed position when the magnetic member is moved into attractive relation with the electromagnet by means of an electromagnetically actuated closing mechanism. The attractive eiiect of the hold ng electromagnet upon the movable magnetic member is under the joint magnetic influence of a shunt holding winding and a bucking bar or wlnding responsive to the current through the switch so arranged as to quickly release the movable magnetic member and thereby permit the switch arm to open upon the occurrence of an overload current. Circuit interruptors constructed and arranged in the manner described in the above application are eminently successful under all ordinary service conditions but when applied to heavy duty circuits where large currents are encountered, the necessarily increased weight v of the moving parts; the increased accelerating force of the biasing springs and the correspondingly increased powerof the closing mechanism, produce impacting shocks which not only may severely rack the structure of the interruptor but also may cause premature releasing of the magnetic member should a current near the overload value flow in the circuit upon closure of the switch arm. Therefore, a further specificobject of the invention is to provide anovel arrangement of control apparatus and circuits whereby the holding winding of such an electromagnetic circuit interruptor may be overexcited automatically upon the operation of the closing -mechanism and maintained over-excited until after the operation of the closing mechanism is completed.

For a better understanding of our invention, reference is bad to the following description taken in connection with the accompanying drawing in which the single figure diagrammatically illustrates a control system for an electromagnetic high speed trip free type of circuit interrupter embodying the invention for the purpose of explaining the principles thereof.

As is more fully set forth in our co-pending application, Serial No. 683,533, filed December 31, 1923, and of which our present application is a division, the principal parts of the circuit interruptor illustrated in the drawing comprise the movable switch arm 10 which cooperates with the stationary contact 11 to open and close an. electric circuit. Switch arm 10 is pivoted intermediate its ends in suitable bearings carried.at one end of the movable magnetic member 12 which in turn is mounted to rotate about the stationary pin 13. A common biasing spring 14 for both magnetic member 12 and switch arm 10 has one end connected to switch arm 10 on the opposite side of the pivoted support from the circuit controlling contact and the other end connected to a stationary adjusting screw 15. The movable magnetic member 12 and the switch. arm 10 thus constitute a compound switch element which is biased as a unit to the open position in which it is shown and the switch arm 10 is biased to the closedposition when the movable magnetic member 12 is actuated to and held in the attracted position.

In order to maintain the compoundswitch element in the circuit closing position, an electromagnet 16. is provided with a shunt Winding 17 for normally exerting SllffiClGIlt magnetic attraction on the movable magnetic member 12 when the latter is operated into attracted relation with the poles of the electromagnet to overcome the opening strain of biasing spring 14. A bucking bar or series winding 18 is interposed in the air gap between the poles of electromagnet 16, as described and broadly claimed in the re-issued patent'to John F. Tritle,'No. 15,441 and more particularly described and claimed in the copending application of Leonhard Haag, Serial NO. 560,216, filed May 10, 1922, each of which is assigned to the same assignee as our present invention. In the particular arrangement illustrated, the bucking bar or series' winding 18 is connected in the power circuit of the generator 19 which is completed from the high voltage supply line 20 through disconnecting switch 21, the low voltage circuit breaker 22-, the armature of generator 19 and the trip free interruptor to ground upon closure of the respective switches. The shunt holding winding 17 of the trip free circuit interruptor is connected permanently from the high voltage terminal of the generator 19 to ground in series circuit with a manually operable control switch 23 which is biased to the closed position as shown and a voltage reducing resistor 24.

The compound switch element comprising the magnetic member 12 and the circuit controlling member 10 is operated to the closed position by means of the electromagnetically actuated closing mechanism 25. The

p energlzing circuit of the closing mechanism 25 is controlled by the relay 26 which is biruptor when closed is arranged to short circuit a current limiting resistor 29 which is permanently connected in the power circuit of generator 19 in order to limit the current therein under overload conditions to a predetermined safe value. Also it will be seen that the series winding 18 of the interruptor may be shunted by a suitable shunt 30 if desired.

As thus constructed and arranged and with the parts in their respective position shown in the drawing, the operation of our improved control system for the interruptor is as follows :Should it be desired to connect the generator 19 to the'high voltage supply line 20, disconnecting switch 21 and the voltage protective circuitbreaker 22 first are moved from the open positions in which they are shown to their respective closed positions. This completes an energizing circuit for the shunt winding 17 of holding electromagnet 16 which may be traced from the supply line 20 through the disconnecting switch 21, circuit breaker 22, control switch 23, shunt winding 17, and the resistor 24 to ground. Thereupon, the normally opened control switch 27 is closed to connect the operating winding of relay 26 in shunt with theresistor 24. This energizes the relay 26 responsively to the voltage drop across the resistor 24. Upon the resulting closure of relay 26 an energizing circuit for the operating winding of the switch closing mechanism 25 is established from the supply line 20 through the switch 21, the circuit breaker 22, the contacts of relay 26 and the operating winding of closing mechanism 25 to ground. It should be noted that closure of the normally opened control switch 27 serves not only to energize the opcrating winding of closing mechanisn1'25 but also to over-excite the shunt-winding 17 of the holding electromagnet 16. This is due to the fact that additional current passes through the winding 17 when the operating winding of relay 26 is connected in .shunt with the resistor 24. This feature of automatically over-exciting the shunt winding 17 during the energization and operation of the closing mechanism 25 is of great practical advantage as it permits the circuit interruptor to close the'power-circuit of generator 19 successfully'when the resultant current flow .through the bucking bar or series winding 18 is only a slight amount below the value at which the magnetic member 12 is released.

Upon the energization of the operating Winding of closing mechanism 25 in the -man ner previouslydescribed, the operating arm 31 of the closing mechanism is rotated into engagement with the lower end of the pivotally mounted switch arm 10 and moves the switch arm together with the magnetic member 12 as a unit about the 'pin 13 against the strain of biasing spring 14; The arrange ment is such that upon the magnetic member 12 arriving at the attracted position in which it engages the pole pieces of holding electromagnet 16, the auxiliary switch 28 is actuated from the, open position in which it is shown to the closed position thereby short circuiting the operating winding of relay 26. After a time delay while the magnetism of relay 26 is decreasing under the retarding influence of the short circuit operating winding thereof, the relay contact drops to the open position according to its bias. This interrupts the energizing circuit of the closing mechanism 25 and permits the switch arm 10 to move into engagement with the stationary contact 11. I

Upon the short circuiting of the operating winding of relay 26 by the auxiliary contact 28, the shunt winding 17 of the holding electromagnet 16 is still further over-excited due to the fact that the resistor24 as well as the operating winding of relay 26-is short circuited upon the closure of auxiliary contact 28. The resulting heavy over-excitation of the shunt winding 17 serves to hold the magnetic member 12in the attracted position irrespective of the jars and shocks necessarily accompanying the closure of the circuit-interruptor and the return of the closing mechanism 25 to the position in which it is shown.

Should the current in the power circuit of the generator 19 increase above a predetermined value after the circuit interruptor is closed, the bucking bar or series winding 18 will affect the release of magnetic member 12 and the consequent opening of the circuit controlling arm 10 in the following mannerz-As the current increases through the bucking bar or series winding 18, the magneto motive force of the bar or winding serves to shift an increasingamount of the flux of the shunt winding 17 from the magnetic member 12. At a predetermined value of overload current, the pull of biasing spring 14 is sufficient to overcome'the attractive effect of. electromagnet 16. Thereupon the magnetic member 12 and the switch member '10 are rapidly moved to the open position and thereby insert the resistor 29 in the generator circuit to maintain the overload current flow within safe limits. Upon the return-of the generator current to normal value, the circuit interruptor maybe operated to the closed position to re-establish the short circuit ar'ound the current limiting resistor 29 in the manner previously described.

In accordance with the provisions of the patent statutes, we have described the principle of operation of our invention together with the apparatus which we now consider to represent the best embodiment thereof but we desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means. c

What we claim as new and desire to secure by Letters Patent of the United States, is

1..-The combination with a device movable to one position-and biased to another position, of a normally energized electromagnet for holding the said devicein the said one position against its bias, electroresponsive means for operating the said device to the said one position, and means controlled responsively to the movement of the said device .to the said one position for simultaneously controlling the energization of said electroresponsive operating means and over-exciting the said holding electromagnet.

2. The combination with a switch member and an electromagnet for holding the same in the closed position, of separate electroresponsive operating means for operating the switch member to the closed position, controlling means' for simultaneously setting said separate electroresponsive' operating meanscinto operation to close the switch and regulating the attractive forceof the said holding electromagnet, and means whereby the said controlling means is operated to render saidswitch operating means inactive position against its bias, a. separately energized electrically actuated means formoving the said device to the said one position, and switch mechanism and electrical connections for-increasing the attractive forceof the said normally energizedelectromagnet when the said electrically actuated means is separately energized.

i 4. The combination with a device movabl to one position and biased to another position of a normally energized electromagnet for holding the said device in the said one position against its bias, electromagnetic means for moving the said device to the said one Pposition, switch mechanism operable to over excite the said electromagnet and energize the said means, and an auxiliary switch acrtuated responsively to the movement of the said device to the said one position for further over-exciting the said electromagnet and deenergizing'the said electromagnetic means.

5. The combination with an electromag= netically actuated device having separate operating and holding windings, of a resistance normally in circuit with the said holding winding and a source of supply, means for independently energizing said operating winding from said source, and switch mechanism and electrical connections for closing a shunt circuit around the said resistance upon energization of said operating winding. i

6. The combination with an electromagnetically actuated, device having an operating and a holding winding,-'of a resistance normally in circuit with the said holding winding, an electromagnetic relay for connecting the said closing winding to a source of supply, and switch mechanism and electrical connections for connecting the winding of the said relay in shunt with the said resistance to simultaneously over-excite the said holding winding and efiect the energization of the said operating winding.

7. The combination with an electromagnetically actuated circuit interruptor biased to the open position and having a closing winding and a holding winding arranged to be normally energized, of a resistance normally connected in circuit with thesaid holding winding, an electromagnetic relay for connecting the said closing winding to a source of supply, a control switch for connecting the winding of the said relay in shunt with the said resistance to simultaneously over-excite the said holding winding and eflect the energization of the said operating winding, an auxiliary control switch for said relay actuated responsively to the movement of the said electromagnetically actuated switch, and electrical connections controlled by the said auxiliary control switch for short circuiting the winding of the said relay upon the closure of the said interruptor.

8. The combination with an interruptor for electrical circuits having a compound switch element biased to the open position, the said element comprising a magnetic member movable from the open position to an intermediate position and a relatively movable c'ontact'arm thereby biased tothe closed position,

to simultaneously over-excite the said electromagnet and effect the energization of the.

of electrically actuated means for operating the said switch element from the open position to the said intermediate position, an electromagnet for holding the said magnetic member in the said intermediate'position, a resistance normally connected in circuit with the said electromagnet, an electromagnetic relay for controlling the energization of the said electrically actuated means, a control switch for connecting the winding of the said relay in shunt with the said resistance a 

